Young women treated for breast cancer have the same survival rates regardless of whether they have the BRCA gene mutation, a study suggests.
The BRCA1 and BRCA2 gene mutations increase a woman's risk of breast cancer by four-to-eightfold.
The study of 2,733 British women also found a double mastectomy did not improve survival rates for patients with the mutation 10 years later.
An expert said women should take time to decide if surgery was for them.
BRCA has been dubbed the 'Angelina Jolie gene', after the actress revealed she underwent surgery on learning she had an up to 87% chance of developing breast cancer.
Mutations in these genes stop DNA repairing itself and increase the risk of cancer developing.
They are also linked to ovarian and prostate cancers, as well as breast cancer.
The study, published in The Lancet Oncology, found 12% of 2,733 women aged 18 to 40 treated for breast cancer at 127 hospitals across the UK between 2000 and 2008 had a BRCA mutation.
The women's medical records were tracked for up to 10 years.
During this time, 651 of the women died from breast cancer, and those with the BRCA mutation were equally likely to have survived at the two-, five- and 10-year mark as those without the genetic mutation.
This was not affected by the women's body mass index or ethnicity.
About a third of those with the BRCA mutation had a double mastectomy. This surgery did not appear to improve their chances of survival at the 10-year mark.
'More time to decide'
The study's author, Professor Diana Eccles, of the University of Southampton, said: "Women diagnosed with early breast cancer who carry a BRCA mutation are often offered double mastectomies soon after their diagnosis or chemotherapy treatment.
"However, our findings suggest that this surgery does not have to be immediately undertaken along with the other treatment."
Surgery may still be beneficial for patients to reduce their risk in the longer term, such as two to three decades after their initial diagnosis.
Fiona MacNeill, of the Royal Marsden NHS Foundation Trust, who was not involved in the research, said: "This study can reassure young women with breast cancer, particularly those with triple negative cancer or who are BRCA carriers, that breast conservation with radiotherapy is a safe option in the first decade after diagnosis and double mastectomy is not essential or mandatory at initial treatment.
She added: "In view of this, younger women with breast cancer can take time to discuss whether radical breast surgery is the right choice for them as part of a longer-term risk reducing strategy."
The authors note the findings do not apply to older women.